Could smell hold the key to ending pesticide use?

University
scientists may have uncovered a natural way of avoiding the use of pesticides
and help save plants from attack by recreating a natural insect repellent.

Scientists from
the School of Chemistry and Rothamsted Research have, for the first time, created
tiny molecules which mirror a natural occurring smell known to repel insects.

The scientists
were able to make similar smelling insect repellent molecules, by providing the
enzyme, ((S)-germacrene D synthase),
which creates the smell, with alternative substrate molecules.

The
effectiveness of the smell or perfume to function as an insect repellent was
tested.

The team found
that the smells repelled insects but in one case a reversal of behaviour – an
attractant - was observed which raises the prospect of being able to develop a
trap-and-kill device.

"We know that
many organisms use smell to interact with members of the same species and to
locate hosts of food or to avoid attack from parasites," according to the Head
of the School of Chemistry, Professor Rudolf Allemann who led the research.

"However, the
difficulty is that scientifically smell molecules are often extremely volatile,
chemically unstable and expensive to re-create. This means that, until now,
progress has been extremely slow in recreating smells that are similar to the
original.

"Through the
power of novel biochemical techniques we have been able to make insect
repellent smell molecules which are structurally different but functionally
similar to the original," he added.

Professor John
Pickett, FRS from Rothamsted Research said: "This is a breakthrough in rational
design of smells and provides a novel way of producing a smell with different
properties and potentially better ones than the original but at the same time
preserving the original activity.

"By using
alternative substrates for the enzymes involved in the ligand biosynthesis
(biosynthesis of the smell) we can create the appropriate chemical space to
reproduce, with a different molecular structure, the activity of the original
smell."

The team hope
that their research could provide a new way of designing and developing small
smell molecules which would be otherwise be too difficult to produce by usual
scientific and commercial methods.